A standard carb overhaul would replace all gaskets, O-rings, and the float valve/seat.
Consider taking this opportunity to replace the old valve/seat with a Grose-Jet from John Titus.
Can the passages be cleaned?
Like most carburetors there are passages (for drilling) that have lead plugs in them.
These plugs can loosen and fall out! leading to Danger
It seems to be primarily age-based, but it's not deterministic. Probably the less time running, the more likely.
But note that even if they are not loose, the passages may have accumulated debris that is very hard to remove.
These passages are hard to clean, and just soaking will likely not remove it all.
So what are my options?
The plugs can be removed, the passages cleaned, and either plugs or screws reinserted.
Where are the plugs?
Remove the plugs from one carb and check for junk in the lower front
to back passage, (see my photo #11 in Fuel system photos) that is the
hard stuff that came out of all 3 of mine. If the passage is clean
and clear move on to the others. I used a #36 drill, as I recall, in
FINGERS to ream out the passage. You will need to approach from the
front to resistance and from the back to resistance as the passage in
not perfectly line drilled.
I cut 4mm long pieces of 1/8" (3.175mm) diameter "Bridgit" a low
temperature non lead solder for copper pipe fittings. It is made by
J.W. Harris Co. Cincinnati, Ohio. It contains Antimony, Tin, Silver,
Copper, and Nickel. It comes in a 1 pound roll.
to Solder and the last item, Stay-Safe Bridgit.
Then tapped the plugs in with a flat punch, slightly larger than the
hole. then put a drop of penetrating Loctite (green) on each one then
covered with a dab of Epoxy Steel J-B Weld.
Nothing wrong with RED Loctite if you applied it to the plug before
you tap it in. My idea of Loctite came after I had the plugs in and
I used the GREEN penetrating to have it seep in as best it could.
The J-B Weld is the really holding material to prevent the plug from
falling out if it gets loose. Also you can periodically inspect all
the plugs with a mirror later and insure the J-B Weld is in place.
Mike, Any suitable soft plug will work. I wouldn't use a steel ball
as it would have to be sized exactly and even then it might crack the
housing if it was the least bit too big!
I do the same, put tread on it, easy to clean the DCNF in the future
only the 2 in the petrolchamber this 2 are welded.
The lower 7 plugs are usually the only ones that need to be removed
and checked for clear passages. The 2 in the float bowl are not
counted in the 7 to be removed.
I use brass bolds ( metric 4 mm ) with locktide, the bolds so much as possible
on the DCNF, in the floating chamber you can also use bolds and nuts with